Safety device for lift beds

ABSTRACT

On a foot-controlled operating element for motor-driven items of furniture, particularly lift beds ( 1 ) and treatment couches, with a motor-driven lifting mechanism and a foot switch for operating the drive, where the drive function can be activated by exerting a load on the foot switch, provision is made, for the purpose of deactivating the drive motor of the lifting mechanism, preferably reversing the lowering movement until the operator&#39;s foot is released, for the foot switch to display at least a second switching step, which can be triggered by increasing the operating force exerted by the foot beyond the normal load value, and stops the downward movement of the item of furniture.

The present invention relates to a safety device for motor-driven items of furniture, particularly lift beds and treatment couches, particularly a safety cut-out to prevent excessive lowering of the item of furniture.

Modern lift beds, treatment couches and the like, such as used in hospitals and sick wards, permit lowering of the reclining surface almost to ground level. Lowering and raising of the reclining surface is accomplished, for example, via bedposts designed as lifting columns, bell-crank or scissor systems driven by motors. The drive is often operated via foot switches in order to leave the nursing staff's hands free for other tasks, such as supporting the patient or handling infusion or breathing apparatus. The foot switch is generally positioned beneath the reclining surface in the vicinity of the edge of the reclining surface, so as not to pose a risk of stumbling. It is connected to the drive motor(s) for the lifting mechanism simply via a free, unguided cable. When operating the switch, the operator puts a foot under the reclining surface and steps on the switch. If the reclining surface is lowered too far in this context, the foot may become trapped, meaning that the switch can no longer be released, and the lowering movement of the lift bed or the treatment couch thus no longer be brought to a halt. This can lead to contusion of the foot of the person operating the switch.

The object of the invention is to describe a foot switch and a switching device which, in the case described above, cause the drive motor of the lifting mechanism to be shut down, preferably reversal of the lowering movement until the operator's foot is released.

The object is solved by a foot-controlled operating element for motor-driven items of furniture, particularly lift beds and treatment couches, with a motor-driven lifting mechanism and a foot switch for operating the drive, where the drive function can be activated by exerting a load on the foot switch, and the foot switch displays at least a second switching step, which can be triggered by increasing the operating force exerted by the foot beyond the normal load value, and stops the downward movement of the item of furniture.

Preferably, triggering of the second switching step reverses the downward movement of the item of furniture into an upward movement for as long as the load necessary for triggering the second switching step persists on the foot switch.

Preferably, low-voltage DC motors are used as the electric drives.

Two-step switching can be accomplished in such a way that the switching contact of the first step is released when the (second) overload switching step is reached, thus returning to its starting position. In this context, a pole reversal function can be wired to take effect simultaneously or after further, short switch travel, this bringing about a reversal of the lowering movement of the item of furniture.

A practical example of the invention is described in more detail below on the basis of the drawing. The drawing shows the following: FIG. 1 A perspective view of a lift bed with foot-controlled operating element.

FIG. 1 shows an example of a lift bed 1, the bedposts of which are designed as telescopic lifting columns 2, each of which displays rotary spindles. The drive function is provided by electric motors 3, whose drive axle reaches into bridge 4, on which two lifting columns are located in each case, from where it acts on the spindles on both sides by means of toothed belts. Foot-controlled operating element 5 displays two pedals 5.1 and 5.2 in the form of spring-loaded rockers, one of which triggers the upward movement of the bed when loaded, the other triggering the lowering movement. The operating element is positioned in free-standing fashion under the bed and connected to motors 3 via leads 6. In this context, the motors are connected in parallel as regards the switches. 

1. Foot-controlled operating element for motor-driven items of furniture, particularly lift beds and treatment couches, with a motor-driven lifting mechanism and a foot switch for operating the drive, where the drive function can be activated by exerting a load on the foot switch, characterized in that the foot switch displays at least a second switching step, which can be triggered by increasing the operating force exerted by the foot beyond the normal load value, and stops the downward movement of the item of furniture.
 2. Foot-controlled operating element according to claim 1, where the drive can be reversed by triggering the second switching step, in that the polarity of the output voltage is reversed, for as long as the operating force, exerted by the foot, necessary for triggering the second switching step persists.
 3. Foot-controlled operating element according to claim 1, where one relay each is provided for switching the two poles of the drive. 